# Math Help - Help with series

1. ## Help with series

Hello everyone, I'm kind of new here so wasn't sure where to post a series problem.

How would one go about summing

$\displaystyle \sum_{i=0}^{\infty} \frac{1}{(3i)!}$

I've tried to find similarities between it and the taylor series of hyperbolic cosine, but it isn't really working. I've tried repeated integration to derive a result with the factorial in the denominator but again, I get a non-convergent integral. Any help would be appreciated, thank you.

2. ## Re: Help with series

Hi,
Your problem has a straight forward solution, but the details require some computation. The attachment shows how to solve the problem, but I left the algebraic details to you: